Parallels has interesting ideas that only half work, and Fusion adds almost nothing new beyond better hardware support

Every time there's a new version of OS X, there's also a new version of Parallels Desktop and VMware Fusion, the two desktop virtualization products that let you run Windows, Linux, and OS X in virtual machines on your Mac. As Apple has sped up the pace of new OS X versions, the Parallels and Fusion upgrades have gotten, well, skimpier, with fewer compelling new features.

Yet the price remains the same: for Parallels, $50 to upgrade from the previous version, and $80 from any version before that or for new purchases; for Fusion, $50 to upgrade from the previous two versions, $60 otherwise. Like last year's upgrades, this year's versions fail the value test. It's becoming a tax on using Windows on a Mac, and most people I know rarely fire up Windows on their Mac after the first few months of switching, unless their business requires it.

With the imminent arrival of OS X Mavericks, Parallels has released Parallels Desktop 9 and EMC VMware has released VMware Fusion 6. You can run the previous versions -- 8 and 5, respectively -- in Mavericks, so you don't have to get a new version to maintain compatibility with Apple's latest OS. Although both companies tout "new" Windows 8.1 and OS X Mavericks guest-OS compatibility in their new versions, I ran Windows 8.1 Preview and OS X Mavericks beta just fine in the previous versions. Further, OS X Mavericks beta runs both products' previous versions without a hitch. You don't need a new version of Parallels or Fusion just because of OS X Mavericks or Windows 8.1.

Because the OS updates are compatible with older versions of the virtualization programs, it becomes even more essential that the upgrade price match the new capabilities' value.

Of the two, Parallels Desktop has the greater number of interesting features (it did last year as well) -- ironically, they're meant to improve Windows 8 by adding a true Start menu and by making it work more like OS X.

VMware Fusion 6: Nothing much new hereMost of Fusion 6's enhancements are under the hood. You can allocate more RAM to each VM (64GB, up from 8GB) and use larger drives (8TB, up from 2TB). Fusion 6 also supports -- as any app does, with no modifications needed -- new OS X Mavericks capabilities such as the options for multimonitor setups that let you put a full-screen app window in its own desktop and use an Apple TV-connected monitor as if it were a monitor attached to your Mac.

VMware didn't take the opportunity to standardize how it maps the Windows key commands in Fusion; as in the last version, sometimes you press Command and sometimes you have to press Cmd-Shift with the key to get the Windows key equivalent. That's a real usability blocker.

In other words, Fusion 6 is not much of an upgrade. Make no mistake: Fusion is a fine product, but there's no reason to pay $50 for the current version.